Alkylation process with normal paraffin removal



O. WEBB, JR

Sept. 24, 1963 ALKYLATION PROCESS WITH NORMAL PARAFFIN REMOVAL Filed.June 5, 1961 4 Sheets-Sheet l @SAME my @WWW O- WEBB, JR

Sept. 24, 1963 ALKYLATION PROCESS WITH NORMAL PARAFFI'N REMOVAL (IUD QQNSN IN V EN TOR. r/a/Ma We) .//I BY y Sept. 24, 1963 o. WEBB, JR

ALKYLATION' PROCESS WITH NORMAL PARA'FFIN REMOVAL Filed .June 5, 1961 4sheetsfsheet s O. WEBB, JR

Sept. 24, 1963 ALKYLATION PROCESS WITH NORMAL PARAFFIN REMOVAL FiledJune 5, 1961 4 Sheets-Sheet `4 INVENTOR. ///fao l/V, .//2 BY 0 A @QA/EKUnited States Patent O 3,105,102 ALKYLATIN PRCESS WiTH NGRMAL PARAFFDJREMQVAL Orlando Webb, Jr., Prairie Village, Kans., assigner to StratfordEngineering Corporation, Kansas City, Mo.,

a corporation of Delaware Filed .lune 5, 1961, Ser. No. 114,999 37Claims. (Cl. 26d-683.58)

This invention rela-tes to alkylation processes employing normalparatlinic hydrocarbon elimination from the system and refers moreparticularly to such alkylation pro-cesses employing molecular sicvesfor normal parainic hydrocarbon elimination.

This `application is a continuation-in-part of my application Serial No.748,833, tiled July 16, 198, now U.S. Patent No. 3,055,958, entitledAlkylation Eluent Flash Vapor-ization System.

The art is Well cognizant of the use of molecular sieves for separatingvarious types of hydrocarbons, such as aliphatics from aromatics,straight chain from branched chain, and the like. 'Ihe following patentstypically show the general state of the art in the application ofadsorptive sieve beds and the like in separating various types ofhydrocarbons, one from the other: Ricards 2,899,474, issued August ll,1959, Feed Pre-Treat in Hydrocarbon Adsorption Process; Patterson et al.2,901,519, issued August 25, 1959, Molecular Sieve Separation Process;Gilmore 2,921,970, issued January 19, 1960, Process for SeparatingNormal Aliphatic Hydrocarbons Using Zeolitic Molecular Sieves; Haensel2,920,037, issued January 5, 1960, Separation of Normal Paraflins FromHydrocarbon Mii-:tures Using Zeolitic Molecular Sieves; Fleck et al.2,935,467, issued May 3, 1960, Fractionation Process Using ZeoliticMolecular Sieves; Feldb'auer, Jr., et al. 2,944,092, issued July 5,1960, Gasoline Hydrocarbon Separation Recovery Process Using ZeoliticMolecular Sieves.

The application of molecular sieve separation processes and adsorptiveseparation processes into alkylation processes wherein isoparafiinichydrocarbons are alkylated with olefinic hydrocarbons in the presence ofacid catalysts is also known to the art. Thus, Stiles 2,920,125, issuedJanuary 5, 1960, Regeneration of Adsorbent Matcrials Used in Treating anAlkylate discloses separation of the produced alkylate and acidiccontaminants thereof. Smith 2,935,543, issued May 3, 1960, AlkylationProcess discloses the isomerization of a straight chain hydrocarbon feedinto an isomeric mixture comprising the straight chain hydrocarbon and acorresponding isomeric branched chain hydrocarbon with the isomatesubjected to contact with the molecular sieve thereby preferentiallyadsorbing straight chain hydrocarbons to the exclusion of thenonstraight chain hydrocarbons. The branched chain hydrocarbons are thenintroduced int-o the alkylation zone with olelins and catalyst in aconventional reaction step. W. L. Vermilion, Jr., 2,946,832, issued July26, 1960, Alkylation Process discloses, in an alkylation process, thepassage of the hydrocarbon phase eifluent after removal of residualacids to a deisobutanizer, the overhead from the deisobutanizer 'beingpassed to a molecular sieve bed to separate normal butane fromisobutane, the latter being recycled to the reaction step.

An object of the instant invention is to provide means and steps forstrategically removing normal paratlinic hydrocarbons from an alkylationsystem reaction effluent whereby to more greatly enhance the desirablecharacteristics of the reaction step and other parameters of thekylation system than previously achieved.

Another object of the invention is to provide ways for removing normalparalinic hydrocarbons from an alkylation system reaction effluent toachieve the said results employing molecular sieve adsorption beds.

Yet another object of the invention is to permit the replacement, in `analkylation process employing normal parain removalV therefrom, of theconventional deisobutanizer fractionation column with very much simpliedand lower cost isostripper column, requiring no reilux therefrom and yetproducing a very high purity recycle. Another object of the invention isto provide -an alkylation process employing normal parar'inichydrocarbon elimination wherein recycle feeds to the reaction step areprovided which are abnormally high in isobutane content whereby to makethem far more effective in lbuilding up the isobutane concentration inthe alkylation reaction.

Another object of the invention is to provide an alkylation processemploying both effluent refrigeration and normal paraiiin eliminationwherein fla-shed vapors from the etliuent refrigeration suction trap andlight hydrocarbon recycle from the isostripper lare abnormally high inisobutane content, whereby to make them far more effective in Ibuildingup the isobutane concentration in the reaction step.

Another object of the invention is to provide an alkylation processutilizing eluent ash vaporization separation of light hydrocarbons fromthe hydrocarbon phase eflluent and, additionally, normal paraiinichydrocarbon elimination wherein recycled vapors from the alkylationflash vaporization step and also from the isostripper stage areyabnormally high in isobutane content, whereby to make them. far moreeifective in building up the isobutane concentration in the alkylationreactor. v

Another object of the invention is to provide an alkyla tion processwith normal paralinic hydrocarbon removal rorn the system wherein it ispossible to produce alkylate of extremely high quality with improvedboiling range characteristics and with a minimum and unusually low acidconsumption.

Another object of the invention is to provide an alkylation processemploying normal parafnic hydrocarbon removal from the system whereinthe etiiciency of the entire -alkylation unit and process isconsiderably greater than conventional processes due to the reduction ofnormal paraffin hydrocarbon diluent in the system at critical processstages in the system.

Yet another object of the invention is to provide avariety of ways ofnormal parafnic hydrocarbon elimination from alkylation systems wherebyto achieve the many advantages thereof independent of lthe type ofrefrigeration system used (closed cycle or effluent refrigeration) andindependent of the ysystem used in the alkylation process for separationand recycle of isobutane from the reaction eliluent (eluentrefrigeration separation, alkylation ash vaporization, fractionationseparation, etc.)

Yet another object of the invention is to provide a variety of ways ofnormal paranic hydrocarbon elimination from alkylation processes andsystemsemploying molecular sieves, whereby to achieve maximum andcomplete normal parainic hydrocarbon separation, permit a maximumthroughput flow in the alkylation system, provide ample time periods forsieve clearance and desorption, and also provide a multiplicity of flowalternatives for permitting sieve replacement .or repairwithout-shutting down the system.

Other and further objects of the invention will appear in the course or"the following description thereof.

In the drawings, which form a part of the instan-t speciiication and areto be read in conjunction therewith, embodiments of the invention areshown.

FIG. l is a schematic ow diagram of an alkylation unit employing varioustypes of effluent refrigeration of the reaction step and also showingapplication of molecu- 3 lar sieves for normal parainic hydrocarbonelimination from the system.

FIG. 2. is a schematic ow diagram of an alkylation unit employingetiluent refrigeration to cool the reaction step and illustrating asecond manner of employing molecular sieves in said system forelimination of normal para'nic hydrocarbons therefrom.

FIG. 3 is a fragmentary view of a portion of the unit of FIG. 2 showinga variation in position of the neutralization step therein. l

FIG. 4 is a schematic flow diagram of an alkylation unit employing aclosed cycle refrigeration system for the reaction step and an optionalalkylation flash vaporization system for separation of isoparaflinichydrocarbons from the reaction eluent for recycle to the reaction step,a molecular sieve system applied in the unit to provide elimination of-normal paratlinic hydrocarbons therefrom.

FIG. 5 is a fragmentary view of a variation of the unit of FIG. 4showing relocation of the neutralization step therein.

FIG. 6 is a schematic ilow diagram of an alkylation unitemployingvarious types of effluent refrigeration to cool the reaction step andseparate volatile hydrocarbons from the hydrocarbon phase efliuent,application of molectular sieve separation beds being made into thesystem at various points to separate normal parainic hydrocarbondiluents from the reaction eluent.

FIG. 7 is a fragmentary view of a portion of the alkylation unit of FIG.6 showing relocation of the neutralization step therein.

FIG. 1-N0rmal Parajnc Hydrocarbon Separation in Eluent RefrigerationReferring particularly to FIG. l, at 10 is shown the shell of a reactorequipped 'with an open-ended circulating'tube 11. At one end of thecirculating tube is an impeller 13 which serves the purpose of acirculating pump in cooperation with the circulating tube. Within thecirculating tube 11 are a plurality of heat exchanger elements 14comprising a tube bundle provided with a distributing head 1'5 enclosingone end of the reactor. The impeller 13 is mounted on a shaft 16 rotatedthrough a reduction gear 17 by any suitable source of power or primemover such as an electrical motor or steam turbine diagrammaticallyshown at 18.

Circulation within the reactor is established by the impeller throughthe annular space between the shell 10 and circulating tube 11 aroundthe cooling or heat exchange -tubes 14 and back to the impeller. Olenichydrocarbons and isobutane in excess are introduced to the systemthrough lines 19 and 20, respectively, and are combined in feed pipe 21prior to passage through heat exchanger 22. Recycled isobutane fromfractionation is returned through line 23 and introduced into thehydrocarbon mixture before the latter reaches heat exchanger 22,constituting a portion of the feed supplied to the reactor through line24.

Fresh acid is supplied to the system through line 25 being combined withrecycle acid bottoms through line 26 from acid settler |27. The mixedacid is passed to the reactor through line 28.

Hydrocarbons supplied through -lines 19 and 20 combined with recycledisobutane are mixed in the reactor with the acid catalyst introducedthrough line 28. Akylation of the `isoparathnic hydrocarbons by theolenic hydrocarbons takes place in the reactor while the mixture isbeing rapidly circulated and agitated by impeller 13 which assuresmixing of the hydrocarbons in acid catalyst.

Y The eluent mixture of hydrocarbons and acids is discharged from thereactor through line 29, passing rst to the acid settler 27 where it ispermitted to separate into a hydrocarbon phase and an acid phase. Theacid phase is withdrawn from the bottom of the settler and returned tothe reactor through lines 26 and 28. As a separate additional source ofisobutane alternatively or concurrently usable with feed line 20,particularly with isobutane of low purity (below line 30 passes fieldisobutane makeup into dryer 31, which Vcomprises simply a drum withconcurrent flow of spent alkylation acid from line 32 and makeupisobutane, which for this flow diagram may be assumed to be of lowisobutane purity. With the acid dryer, moisture will be removed from themakeup isobutane stream before being introduced to the sieve system tobe described and corrosion will be avoided. Acid is taken from the dryerby line 33 and the dried isobutane makeup stream goes into the systemthrough line 34.

The hydrocarbon phase separated in settler 27 is discharged from the topthrough line 35. From the top of the acid settler, in an euentrefrigeration system, a number of alternatives are possible. Typicaleffluent refrigeration and evaporative cooling systems for alkylationprocesses are shown in the patents to David H. PutneyY Nos. 2,664,452,issued December 29, 1953, Process for Alkylation Utilizing EvaporativeCooling and 2,949,494, issued August 16, 1960, Alkylation ofHydrocarbons Utilizing Evaporative Cooling.

In a first modification of the invention applied in an eilluentrefrigeration system, the hydrocarbon phase eluent, wholly or in part,is passed into line 36, controlled by valve 37. This hydrocarbon phaseeffluent picks up the isobutane makeup stream from line 34 and then maybe passed Wholly or in part into either or both of lines 38 and 39,controlled by valves 40 and 41, respectively. In the event that all ofthe hydrocarbon phase eluent passing through line 36 is passed throughline 38, no normal parainic separation is made from this eiuent beforereaching the suction trap of the effluent refrigeration system. On theother hand, if all or any of the hydrocarbon phase effluent in line 36is passed through line 3-9, controlled by valve 41, normal parainicseparation may be made therefrom as will be described.

Lines 42 and 43 controlled by valves 44 and 4S, respectively, pass tomolecular sieves 46 and 47. The sieves are such as separate normalparanic hydrocarbons inV the chain length of the system from isoparanichydrocarbons. The sieve showing in this and t-he other figures arepurely schematic. Normal parainic hydrocarbons are removed from sieves46 and y47 through lines 148 and 49 controlled by valves '50 and 51,respectively, the lines joining in output line 52. Isoparafiinichydrocarbons are removed from lthe sieve through lines 53 and 54,controlled by valves 55 and 56, respectively, these lines joining inline 57 iwhich meets bypass line 38, resulting in common line 59. Fromline 59, the hydrocarbon phase eiuent, normal paraffin extracted to agreater or lesser degree, may be passed into either line 60 or line 61,controlled by valves 62 and y63, respectively. It should be noted thatthe molecular sieve system operates preferably with one sie-ve on streamuntil it is fully loaded and ready for desonption, with the other sievethen -being put in the stream and so on. The hydrocarbon phase eluentpassed into line `60 is pressure reduced at valve 64 and Ifrom thencepassed 4at greatly increased velocity into the distributing head whichis divided by baffle 15a whereby the hydrocarbon phase eiiuent, bothliquid and vapor, passes through the tube bundle, cooling the reactionstep and vaporizing excess light hydrocarbons in the eiuent and out theother side of the distributor through line 65 to suction trap 66.Alternatively, or simultaneously, the hydrocarbon phase efliuent may bepassed to greater or lesser degree through line 61, pressure reduced atvalve 67 and thence passed through line I68 to the suction trap.

Returning to the acid settler and the line 35 taking the hydrocarbonphase fromy the upper portion thereof, alternatively, the hydrocarbonphase ei-uent may be passed entirely or to a greater or lesser degreeinto line 69, controlled by valve 70. :From valve 70, the hydrocarbonphase eflluent may be passed into either or both lines 71 and 72,controlled by valves 73 and 74, respectively. In the event thehydrocarbon phase effluent is passed in at least some part into line 71through valve 73, it is passed through lines 74 or 75 controlled byvalves 76 and 77, respectively, to molecular sieves 78 or 79.Normaliparallinic hydrocarbons are removed from said sieves by lines Stiand 31, controlled by valves y32 and 83, respectively, the normalparaffinic hydrocarbons carried oft" through common line 84. Branohedchain hydrocarbons are returned from the sieves through lines 85 and 86,controlled by valves 37 :and d3, respectively, passing into common lineS9. The latter is joined by line 72 after the outputs for the branchedchain hydrocarbons from the sieves. Again, this sieve system is run inconventional fashion in the sense that one sieve is employed `until itis completely loaded with adsorbed material, then it is taken out ofstream by valve control and the other sieve put into stream Iwhile therst is desorbed; :In any sieve system referred to in this application,more than two sieves unay be employed as required to keep the systemcontinuously on stream.

Line 72 serves as a bypass option in the event that it is desired topass the hydrocarbon phase eliiuent from acid settler 27 through line'69 to greater or lesser degree, but also to use the sieve system togreater or lesser degree, optionally providing complete bypassoccasionally when the sieves 46 and 47 may be those only employed. Fromline 89 or line 72, the hydrocarbon phase eluent, with greater or lessernormal parafiinic elimination therefrom is passed into common line 99,pressure reduced at bach pressure valve 91 and passed to suction tra-p66. Back pressure valves 91, `64 and 67 maintain sunicient back pressurein the system to keep .the Ihydrocarbons in liquid phase throughout thesieve extraction, if such is desired. The back pressure valves may be sopositioned on lines 69, '71, 72, 36, 39 and 38 as to reduce pressurebefore the sieve systems, if desired.

In the event that the hydrocarbon phase eliluent came -to trap 66through line 0' or through line 68 to any measurable extent, it willprobably be desirable to recycle liquid bottoms through line 92,controlled by valve 93 into line '60 after valve 64 in order to getgreater heat exchange :in the reaction step whereby to cool the reactionstep and vaporize excess volatile hydrocarbons from the liquid bottomsof the trap. Even where all of the hydrocarbon phase eEduent is passedthrough line 6i?, this may be desirable to achieve the greatest heatexchanging effect.

it should be observed that, with `the sieve systems shown, all of thehydrocarbon phase eluent can be normal paraffin stripped by passingthrough lines 69 and 71 or, alternatively, all can be normal parainextracted by passing through lines 36 and 39. Bypass at either lines 72or 38 leaves some hydrocarbon phase effluent'not normal paraffinstripped. Yet alternatively, the hydrocarbon phase eluent can be splitbetween lines 36 and 39 and lines 69 and 71, respectively, and still beentirely normal paraiin stripped. This gives a great deal of versatilityand freedom in handling the sieve systems and also permi-ts a largervolume how-through in the entire system when both are used than througheither system alone.

From trap 66,V light hydrocarbon vapors are passed olf overhead throughline 94 for compression and condensation at 95 and 96 and passagethrough line 97 to accumulator 9S. These vapors will be abnormally rhighin isobutane if the normal paramnic hydrocarbons have f 5 step Vat 22 toa neutralization stage at 106. It should be particularly noted that, inthe case of the sieve systems shown, if the catalyst acid will damagethe sieves, the neutralization step may be placed before the sieves(between the settler and the sieves) rather than after. Fromthencethrough line 1107,' thel neutralized heavier hydrocarbons,carrying some isoparaflnic hydrocarbons as diluent, are passed through aheat exchanging step at 108 through line' 109 to isostripper 110.Isostripper 110 vmay substitute for a large scale deisobutanizer atlthis point due to the previous removal of the greater portion of thenormal paraifinic hydrocarbons in one of the sieve systems whereby thebottoms from the trap are also` abnormally rich in isobutane andabnormally poor in normal parafflnic hydrocarbons. Alternatively, and inall instances Where isostrippers are employed in this disclosure, areiluxing deisobutanizer may be employed. The bottoms from theisostripper are reboiled at 111, While the alkylate is taken olftherefrom through line 112, heat exchanging the feed to the isostripperat 108 and out through line 113. The overhead from the isostripper, veryrich in isobutane and poor Iin diluent normal parafnic hydrocarbons ispassed through line 114 to a condensing step at 115 and thence toaccumulator 116. From accumulator `116, the liquefied isoparaflinchydrocarbons are passed through line 23 to join lines 19 and 20 as arecycle feed constituenty to the reaction step.

It should be noted that it is critical in fthe eliuent refrigerationsystem, however it is employed, to extract the normal paraliinichydrocarbons from the hydrocarbon phase effluent from the acid settlerbefore they reach the suction trap, as, from that stage,'they are takenoff as bottoms or overhead mixed with the recycle feed constituents. Inorder to clear the isobutane recycle feed constituents from the overheadfrom the suction trap, the paraffinic separation mus-t come before therecycle and, in order to clear the feed to the isostripper and avoid thenecessity of an expensive deisobutanizer, again, the hydrocarbon phaseeuent must be stripped preferably before the separation at the trap andat any rate before passage to the isostripping stage.

FIG. Z-Normal Parnfnc Hydrocarbon Separation In Enent Refrigeration(Modification) Referring -to FIG. 2, the alkylation reactor, itsinternal structure and function, and the feed lines thereto andwithdrawal lines therefrom are identical to those those of FIG. l up toand including numeral 35. Thus, the description of FIG. 1 up to andincluding the description of line 35 from the top of the acid settler isherewith incorporated and the same numbers will be applied to FIG. 2,except primed.

The hydrocarbon phase eflluent from the top of acid settler 27 is taken0E through line 35 and passed alternatively or simultaneously throughlines 200 and 2.01, controlled by valves 202 and 203, respectively. Inthe event that the hydrocarbon phase eiuent is passed in whole orV inpart through line 200, it may pick up dried isobutane feed from line 34,and then is passed to a pressure reduction step at valve 204 and fromthence into one side of header 15', through the heat exchange coils 14',out the other side of the header and through line 205 to suction trap206. Thus the portion of the hydrocarbon phase elluent passing throughline 2130 heat exchanges the reaction step and has excess lightparaflnic and isoparainic hydrocarbons vaporized therefrom by the heatof the reaction step.

On the other hand, the portion of the-hydrocarbon phase effluent whichmay be passed through line 4201 is pressure reduced at back pressurevalve 207 and passed also to suction trap 206. To the extent that thehydrocarbon phase eilluent is passed through line 201 or, in order toachieve additional heat exchanging benets in the reaction step, liquidbottoms from suction trap 206 may be recycled through line 208controlled by valve 7 A209 into line 200 just before the header 15'. Aneducation step may be employed at this juncture, as in the same juncturein FIG. 1, if desired.

The resultant process in suction trap 206 is to vaporize lightisoparainic and paraflinic hydrocarbons, taken oit the top through line210, compressed and condensed at 211 and 212, then passed through line213 to accumulator 214. Bottoms from the accumulator are then recycledthrough line 215, pump 216 and line 217 joining feed line 21 as arecycle feed constituent.

lIt should be carefully noted that there has been no reduction in thenormal paranic hydrocarbon diluents relative to the reaction step atthis point, thus the light isoparalrinic hydrocarbons recycle from thetop of the suction trap 206 back into the reaction step is Withoutreduction of the normal parainic diluent therein.

Liquid bottoms from the suction trap are taken off through line 218,controlled by level control 219, driven by pump 220 through controlvalve 221. From valve 221, line 222 passes the suction trap bottoms,including alkylate, diluent normal paraflnic hydrocarbons, diluentisoparafinic hydrocarbons, etc. to a heat exchanging step at 22. Fromthe heat exchanging step at 22', line 223 may be passed optionallythrough line 224 controlled by valve 225 or into line 226 controlled byvalve 227. The latter line passes to the molecular sieves 22S and 229through lines 230 and 231, controlled by valves 232 and 233,respectively. Bypass line 224 may be employed to entirely bypass themolecular sieve section in case the sieves are down entirely for somereason or may bypass a percentage flow from line 22B to lighten the loadon the sieve system. On the other hand, the entire charge from line 223may be passed alternatively into the sieves 228 Yand 229, controlled bythe valves 232 and 233.

Normal parafnic hydrocarbons are removed from the molecular sievesthrough lines 234 and 235 controlled by valves 236 and 237,respectively, lines 234 and 235 feeding into common withdrawal line 238.The branched chain hydrocarbons, including alkylate yand diluentisoparafnic hydrocarbons lare taken o the sieves by lines 2,39 and 240,controlled by valves 241 and 242. Common line 243 joins 224 in a commonline 244 and passes to a neutralization stepV diagrammatically indicatedat 245. 'Ilhe neutralization step may :be placed before the sieves ifthe catalyst will damage same (FIG. 3). The neutralized isoparainicdiluent hydrocarbons and alkylate then pass through line 246 to a heatexchanging step 247 and thence through line 248 to isostripper 249.'Ilhe isostripper has a reboi'ler 250, with -alkylate bottoms therefromtaken ot through line 251, passing through the heat exchanging step withthe feed to the isostripper at 247 and then out of the system throughIline 252. Overhead from the isostripper is taken off through line 253,comprising largely isoparafnic hydrocarbons, is condensed lat 254 andaccumulated at 255. The return line 23' passes the recycle isoparafiinichydrocarbons, freed Afrom normal paraffinic diluent to |a greater orlesser degree, back to the common feed line 21.

Comparing the system of FIG. 2 to that of FIG. 1, the fresh teeds ofisobutane are noted at 20' and 30 in FIG. 2 and 20 :and 30 in FIG. 1. InFIG. 1, normal parainic diiuents may be entirely or to a greater orlesser degree removed from the hydrocarbon phase eluent before reachingthe suction trap. Thus the recycle from the suction trap overheadthrough line 101 in FIG. l is very rich in isobutane content andsubstantially possibly normal parafflnic hydrocarbon diluent free.Additionally, the bottoms Vfrom the suction trap passed over throughlines 102 and 107 to the isotripper -are substantially possibly normalparatnic hydrocarbon diluent free so that the isoparainic hydrocarbonrecycle from the isostripper overhead through line 114 and 23 is alsoabnormally rich in isobutane. Thus FIG. l Iprovides normal paranicelimination, as desired, from all recycle feed streams to thereactionvessel. On the other hand, FIG. 2, not removing normal parainichydrocarbon diluent until after the suction trap stage, fails to controlthe normal parainic content in the suction trap overhead recycle andonly removes normal paraflinic diluents from the bottoms from thesuction trap. However, and this is a critical economic point,nevertheless, the molecular sieve arrangement of FIG. 2 does unload thealkylate-isoparafiinic separation step designated as an isostripper stepat 249 in' FIG. 2, thus making :a rgreat saving possible in this pieceof equipment. Additionally, the isobutane rat-io in the reactor is morefavorable by la substantial margin than it would rbe without the normalparainic diluent removal shown lin FIG. 2.

FIG. 3 shows a variation of the system of FIG. 2 where theneutralization step is emplaced before the sieve system. All of theparts remain the same except their relative position is moved.Therefore, all of the parts are numbered the same, but primed.

The molecular sieve system of FIGS. 2 `and 3 is operated in the samemanner as those described in FIG.Y l, namely, one sieve is employed at atime until it is completely adsorbed, then it is taken olf stream withthe other sieve taking the load while the rst one is desorbed. Theaction then moves back and forth between the sieves or between membersof such series of sieves 'as may be set up to handle the particular ilowdesired.

FIGS. -6 and 7-Normal Paranz'c Hydrocarbon Removal From EffluentRefrigeration System Both Before and After S uctz'ort Trap The systemsof FIGS. 6 and 7, constituting an extension of the systems of FIGS. l, 2and 3, will now be described. As the operating system and arrangement ofparts and hookup is identical to that of FIG. 1 until passing throughthe control valve of the bottoms from the suction trap passing tofractionation, neutralization Iand the like, the `description of partsin operation of FIG. l is incorporated in its entirety Withoutduplication here and the parts will lbe numbered the same, but doubleprimed, to distinguished both yfrom FIG. 1 and FIG. 2.

To briey reca-pitulate the operation of the FIG. 6 system up to thecontrol valve 105", the reaction step and reactor involved are cooled byeluent refrigeration, in that, the hydrocarbon phase effluent from acidsettler 27" is passed through line 35" and then split between lines 69and 36 or alternatively sent through either of them solely. That portionof the hydrocarbon phase eiliuent passing through line 36" picks up newisobutane from line 34 and may lbe normal paraifn extracted to a greateror lesser degree in the sieve system 46 an'd 47. A neutralization step(not shown) may be inserted before the sieve, if desired. From thence itmay be passed directly, atter pressure reduction to the trap throughline 68" or pressure reduced at valve 64 and thence passed through thereaction vessel in heat exchange therewith to the trap 66. That portionof the hydrocarbon phase eluent passed through `line 69 may be normalparain eliminated in the sieve system 79" 4and 78 or bypassedtherearound through line 72, the euent then being pressure reduced atback pressure valve 91 and thence passed into the suction trap 66".Again, -a neutralization step may precede passage to the sieve.

The vapor overhead from the suction trap through line 94" thus may beentirely or to :a greater or lesser degree normal parailin eliminated sothat the light hydrocarbon recycle feed to line 24" through line 101" isabnormally high in isobutane content. Secondly, the liquid bottoms fromthe suction trap taken olf through line 10 may be entirely or to agreater or lesser degree normal parafnic hydrocarbon eliminated so thatthe material passed out :off the suction trap 66" through line 102 isabnormally high in isobutane content whereby any light hydrocarbon laterseparated from the alkylate product and recycled to the reaction stepwould substantially raise the 9 a isobutane ratio in the reaction step.Additionally, such n-parafn removal would serve to reduce the load onthe fractionation vessel, permitting the change of this type of vesselfrom an expensive large size deisobutanizer to a vessel characterizedessentially as an isostripper.

However, and this is `the point of the arrangement of FG. 6, in additionto providing the options in etliuent refrigeration to balance the heatand temperature levels in' the reaction step as desired through varyingthe eifluent refrigeration system, and in addition to the desira-Ibility of having the versatility of two sieve systems which permitlarger capacity, more `constant operation time, less hazard of downtime, more freedom of access to the sieves for replacement and repair,etc., additionally, it is desirable to have yet a further parameter offreedom, versatility yand completeness of normal paraifmic hydrocarbonremoval in the system. This freedom, etc. is achieved by the combinationof the molecular sieve system of FIG. 2, namely, that on the linecarrying the suction trap bottoms to the fractionation step, with theefrluent refrigeration sieve systems of FIG. 1.

Referring then to FlG. 6, the suction trap bottoms, normal paraflineliminated to a greater or lesser degree by means of the sieve systemson the hydrocarbon phase effluent lines from the acid settler 27 to thesuction trap 66", are removed from the bottom of the trap through line102", driven by pump 103" and passed to a heat exchanging step with theinput feed of oleiins and isobutane at 22". From the heat exchangingstep, through line 300, the suction trap bottoms may be passedalternatively into lines 391 or 302 controlled by valves 303 and 3%4,respectively. In the event that a portion or all of the suction trapbottoms are passed through line 302, they go into common line 305 andfrom thence to neutralization step 3436. On the other hand, that portionof the suction trap bottoms passed into line Sill are passed into themolecular sieve system, either line 3117 controlled by -valve SS or line309, controlled by valve 310. Sieves 311 and 312 have output lines 313controlled by valve 314 and 315 controlled by valve 316, respectively,meeting `common normal paraiinic elimination line 317 taking ythe normalparaiins out of the system. From the sieve, the alkylate and diluentisoparains from the suction trap bottoms are removed by line 31Scontrolled by valve 319 and line 326 controlled by valve 321 for sieves311 and 312, respectively. Once again, the alkylate and isoparamnichydrocarbons from the sieves are passed into common line 395 to aneutralization step designated schematically at 366. From theneutralization step the neutralized hydrocarbons are passed through line307 to a heat exchanging step with the bottoms from the isostripper at368 and from thence through line 309 to isostripper 310'.

Bottoms in the isostripper are reboiled as at 3111, while the alkylateproduct is taken olf through line 312, heat exchanges the feed to theisostripper at 308 and passed out of the system through line 313. Theoverhead from the isostripper is taken o through line 314, condensed at315 and accumulated at 316 with the isoparanic hydrocarbon overhead,normal paraiiin eliminated to greater or lesser degree, returned to thesystem as a recycle feed constituent through line 23".

Thus it is seen that the greatest versatility with the normal paraffinhydrocarbon elimination and the greatest completeness of such Aisachievable -in the system of FiG. 6. If desired, all or the greatestportion of the normal parafhnic hydrocarbons can be removed in the sievesystems for the suction trap, or either of them, thus completely freeingthe sieve system on the suction trap bottom lines from load.Alternatively, only one of the sieve systems in the eiluent system maybe used to extract all or a lesser portion of the normal paraiiinichydrocarbon diluent before the trap. Yet alternatively, neither of theefliuent systems may be used and only the sieve system '1Q on thesuction trap bot-tom line employed, ,yet achieve major advantages by wayof enriching the isobutane concentration in the reactor and reducing theload on the fractionation step separating the alkylate from the lighthydrocarbon overhead. The use of the sieve systems in the effluentrefrigeration system has an additional advantage in that it minimizesthe load on the entire suction trap system, including the -suction trapitself, and the means for condensing and recycling the vapor overheadtherefrom and passing the vapor overhead therefrom and passing theliquid bottoms therefrom. Yet on the other hand, it may be desirable toemploy the normal parafnic hydrocarbon diluent to a greater or lesserdegree in the efduent refrigerationrsystem as a vaporizable component,depending upon the refrigeration characteristics of the reactor. In suchcase it may be desirable to employ the sieve system in the suction trapbottom removalto a greater degree whereby the normal paranic hydrocarbondiluents fed in through line 341" and 21B will have at least some heatexchanging effect in the reaction step before removal from the system.

Referring to FIG. 7, therein is shown a variation of the FIG. 6 hook-upwherein the neutralization step is replaced before the molecular sievesystem on line 36?. All the parts are numbered the same as in FIG. 6,but primed.

FIGS. 4 and 5-N0rmal Parajjnzc Hydrocarbon Elimination from AlkylationProcess Utilizing Alkylaton Flash Vaporzatz'on System Referring to FIGS.4 and 5, at 49h is shown the shell of a reactor equipped with anopen-ended circulating tube 491. At one end of the circulating tube isan Iimpeller 402 which serves the purpose of a circulating pump incooperation with the circulating tube. Within the circulating tube 461are a plurality of heat exchanger elements 403 comprising a tube bundleprovidedwith a distributing head 464 enclosing one end of the reactor.The impeller l402. is mounted on a shaft 465 rotated by any suitablesource of power or prime mover shown at 406. The circulation in Vessel4% is the same as in the previously-described reactors in the otherfigures and thus will not be redescribed. A reactor or contacter such asthat shown in the application of David H. Putney, Serial No. 669,530,now Patent No. 2,979,308, issued April 11, 1961, Apparatus forControlling Temperature Change of Blends of Fluids or Fluids and FinelyDivided Solids is suitable for use in the hookup of FIG. 4, as well asthe other hookups of the other figures.

`Oletnic hydrocarbons are fed in through line 407, heat exchanged at 498and passed into the reactor before the impeller through the shell andcirculating tube. Isobutane feed or a field stream containing isobutaneis fed in through line 409, joining isobutane recycle lines 416 and 411from the isostripper and eflluent flash systems to be described, passingin common line 412 into the reactor before the impeller. Oletinic feedline 407 and line `412 `may be joined before the reactor, if desired.New acid is input through line 413 joining recycle acid line 414 fromacid settler 415, the combined streams passed by pump 416 through line417 into the reactor before the impeller.

The hydrocarbons supplied through lines 497 and 412 are mixed in thereactor with the acid catalyst introduced through line 417. Alkylationof the isoparainic hydrocarbons by the olefinic hydrocarbons takes placein the reactor while the mixture is being rapidly `circulated andagitated by impeller 462, which assures mixing of the hydrocarbons inthe acid catalyst.

'Ihe efuent mixture of hydrocarbons and acids is discharged from thereactor through line 418, passing first to the acid settler 41S where itis permitted to separate into a hydrocarbon phase and an acid phase. Thereaction eluent hydrocarbon phase is taken olf the top of the acidseparator and settler through line 419. Acid 11 bottoms are taken offthe settler through line 42,0 with depleted acid taken out of the systemthrough line 421 and recycle acid being passed into line 414.

The reactor in FIG. 4 and the reaction step therein is cooled by aclosed cycle refrigeration system. The conventional heating medium forthis closed cycle refrigeration system is passed through line 422 .intoone side of header 404 divided by baile 404:1. 'Ihe refrigerating mediumthen passes through the cooling coils 40'3 and out the other side ofheader 404 into line 423. From thence the heat exchanging medium iscompressed at 424, condensed as at 425 and passed through line 426 toaccumulator 427 from which, through line 428 and after pressurereduction at back pressure valve 429, the medium is again passed intothe heat exchange elements of the reactor. Thus it is seen that thissystem differs completely from the systems of the preceding iigures inthat the hydrocarbon phase euent from the acid settler 415 is notemployed in any way as an eiiluent refrigeration medium for the reactionstep. The entire hydrocarbon phase effluent has been passed from the topof the acid settling step at 415 to heat exchange with the olen feed at408 and from thence may be passed alternatively into either line 420,controlled by valve 421 or into line -422 controlled by valve 423 orsplit therebetween in any ratio desired.

That portion of the hydrocarbon phase efluent passed into line 420 joinscommon line 424 which passes into a neutralization Vstep schematicallydiagrammed at 425. On the other hand, that portion passed into line y422is passed via line 426 controlled by valve 427 or line 428 controlled byvalve 429 to'molecular sieve 430 or alternative sieve 431. Normalparafnic hydrocarbons are passed from sieve y430 by line 432 controlledby valve 433, while they are passed from sieve 431 through line 434controlled by valve 435, lines 432 and 434 joining in common withdrawalline 436. Isoparainic hydrocarbons and alkylate are returned from sieves430 and 431 through lines 437 and 438 controlled by Valves 439 and 440,respectively.

rI'he sieve system in FIG. 4 is operated as the other sieve systems inthat the feed from line 422 is passed lrst to one sieve until it iscompletely adsorbed, then the feed is shifted -to Ithe other sieve fordesorption lof the rst, and vice versa. '[he normal parain eliminatedhydrocarbons are passed into common line 424 to the neutralization step.From the neutralization step, through Yline 441, the neutralized more orless normal paran eliminated hydrocarbons are pressure reduced at backpressure valve 442 and passed into line 443. Back pressure valve 442maintains sufficient back pressure on the entire system to maintain thehydrocarbons in liquid phase. Alternatively, the back pressure valve maybe placed immediately after the acid separation step on line 419 beforethe heat exchange with the oleiin feed at 408. Back pressure valve 442is comparable to valves 91, 64" and 67 in FIG. 6, valves 207 and 204 inFIG. 2 and valves 91, 64 and 67 in FIG. 1. The pressure reducedhydrocarbons are then passed alternatively into lines 444 and 445controlled by valves 446 and 447, respectively. The preferred passage isthe entire hydrocarbon phase effluent, more or less normal paratiineliminated through line 444 into the alkylation ash vaporization drumindicated at 448. Drum 448 has header 449 comparable to header 404 intowhich heating medium such as steam is input through line 450, passesthrough heating coil yor elements 451 in the lower portion of the vessel448 and passes out through line 451 through the opposite side of theheader after adding heat to the contents of the drum. Alternatively, aheater or heating step may be 4emplaced on line 444 before the vessel448,

which comprises basically a flash drum, in place of the in situ coil inthe vessel 448. Volatile hydrocarbons, isobutane to a greater extentaccording to the normal paraffin removal in the sieve system, areremoved overhead through line 452, condensed at -453 and accumulated at454. Bottoms from the accumulator 454 are passed through line 455, pumpy456 and into line 411 as recycle feed to the reactor. Liquid bottomsfrom the alkylation flash Vaporization drum 448, comprising largelyalkylate, are idrawn'off through line 457, joining any by-passhydrocarbon phase eiuent through line 445 and passed through common line458 into isostripper 459.

It should be noted that, when the alkylation iiash vaporization drum isnot employed and all the hydrocarbon phase eflluent is passed throughline 445, the isostripper or fractionation step is only freed of theload of normal parahn diluent removed through the sieve system. On theother hand, when at least some and up to all of the hydrocarbon phaseeilluent is rst passed through the alkylation ash vaporization system at448, the isostripper stage is also relieved of a great relative burdenof llight isoparaiiin removal for recycle to the reaction step and thusthe isostripper vessel may be greatly reduced in size even beyond thatrequired when only the normal parafn diluent is removed in the sievesystem. If an allocation is made between the drum 448 and line 445, thena compromise in Vessel 459 size may be made.

In the isostripper, reboiling takes place at 460 with alkylate bottomswithdrawn through line 461 and passed out of the system. Overhead fromthe isostripper is taken oft through line 462, condensed at 463 andaccumulated in drum 464. The bottoms from drum 464 are taken off throughline 465 by pump 466 and passed from common line 467 either back intothe isostripper through .line 468 or as a recycle feed constituent inline I410.

In comparing the system of FIGS. 4 and 5 with those which have gonebefore, it should be noted that the use of the sieve system before anyisobutane separation and recycle to the reaction step, either from theiiash vaporization drum 448 or isostripper 459, is comparable strictlyto -the normal parafn elimination from the eluent refrigerationhydrocarbon phase effluent streams from the acid settlers in theprevious figures, as opposed to the stripping of the bottoms from thesuction trap in the various preceding figures. Thus a completescavenging of the normal paraflinic hydrocarbon diluent is possiblebefore any recycle to the reaction step whereby to maximize theisobutane concentration there and minimize the normal parailnic diluent.There is no benefit in the alkylation flash vaporization system fromrecycling any normal parainic diluent as it is not employed to cool thereaction step.

Further referring to the FIG. 4 and FIG. 5 systems, it should be notedthat the type of reactor employed at 400 is not critical in that acascade type reactor as shown in FIG. l of the application of OrlandoWebb, Jr., Serial No. 748,833, iiled Iuly 16, 1958 Alkylation EluentFlash Vaporization System could as Well be employed with the hydrocarbonphase eiuent from the cascade type reactor being normal paratlneliminated before passing into the effluent ash drum system thereillustrated.

Referring to FIG. 5, therein is shown a Variation in the system of FIG.4 where the neutralization step is inserted before the sieve system. Allof the parts which are identical are numbered the same, but primed.

Once again, the sieves 430 and 431 are operated alternatively, that is,the feed is to one until it is fully adsorbed, and then the feed isswitched to ,the other while the irst is desorbed and vice versa. Y

The Adsorbent Sieve Systems With respect to the separating step, whereinstraight chain lhydrocarbons are selectively adsorbed from admixturewith nonstraight chain hydrocarbons, it is preferred in the practice ofthis invention to employ as the selected adsorbent, a solid,alumino-si-licate molecular sieve type adsorbent, i.e., adsorbent whichselectively adsorbs 13 straight chain hydrocarbons to the substantialexclusion of nonstraight chain hydrocarbons.

Any suitable selective adsorption process effective for the removal ofstraight chain saturated hydrocarbons from branch chain hydrocarbons issatisfactorily employed in the practice of this invention. y

The invention, however, is particularly applicable to a selectiveadsorbent comprising certain natural or synthetic zeolites oralumino-silicates, such as a calcium alurnino-silicate which exhibitsthe properties of a molecular sieve, that is, matter made up of porouscrystals wherein the pores of the crystals are of molecular dimensionand are of substantially uniform size.

In general, zeolites may beA described as water-containingalumino-silicates having a general formula R, RZO. Al2O3.nSiO2.mI-I2Owherein R may be an alkaline earth metal such as calcium, alkali metalsuch as sodium or potassium or lithium. These materials, when dehydratedfor the removal of substantially all of the water therefrom, retaintheir crystalline structure and are particularly suitable as selectedadsorbents.

A particularly suitable solid adsorbent Vfor straight chain hydrocarbonsis a calcium alumino-silicate, apparently actually a sodium calciumalumino-silicate, manufactured by Linde Air Products Company anddesignated Linde-type 5A molecular sieve. The crystals of thisparticular calcium alumino-silicate have a pore size or opening of about5 angstrom units, a pore size suiiciently large to admit straight chainhydrocarbons, such as the normal paraiiins, 'to the substantialexclusion of the nonstraight chain hydrocarbons, that is naphthenic,aromatic, isoparaiinic and isooleiinic hydrocarbons. This particularselective adsorbent is available in various sizees, such as in the formof I; inch or /l@ inch diameter pellets, or as a iine'ly divided powderhaving a particle size in the range of 0.5-5.0 microns. In general, aselective adsorbent employed in the practice of this invention may be inany suitable form `or shape, granular, spheroidal or rnicrospheroidal.

Particularly suitable so'lid selective adsorbents which may be employedin the practice of this invention include the synthetic and naturalzeolites which, when dehydrated, may be ydescribed I.as crystallinezeolites having a rigid three-dimensional anionic network and havinginterstitial dimensions suiiiciently large to adsorb straight chainhydrocarbons but suicienlty small to exclude the nonstraight chainhydrocarbons possessing larger molecular dimensions. The naturallyoccurring zeolite, chabazite, exhibits such desirable properties.Another suitable naturally occurring zeolite is analcite (NaAlSi2O6-H2O)which, when dehydrated, and when all or part of the sodium is replacedby an alkaline earth metal such as calcium by base exchange use thematerial which may be represented by the formula (CaNaz) Al2Si4O12-2H2Oand which, after suitable conditioning, will absorb straight chainhydrocarbons to the substantial exclusion of nonstraight chainhydrocarbons. Other naturally occurring or syntheticallly preparedzeolites suoh as phacolite, gmelinite, harmotome and the like, orsuitable base exchange modications of these zeolites may also beemployed in the practice of this invention.

Other solid inorganic or mineral selective adsorbents are known. It iscontemplated that selective adsorbents having the property ofselectively adsorbing straight chain i 1d 777,232, also U.S.Patent'2,442,l9l, and the United States patents listed in the preambleto this application, whichare incorporated herein by reference.

The separation of the normal paraflins efrom the isoparaiins may beaccomplished by contacting the hydrocarbon feed mixture in either liquidor vapor phase with the absorption bed. In the event that vapor phasecontact is preferred, the back pressure valves 442, 91, 64, 67, 207,204, 91, 64 and 67 are preferably inserted before the sieve systems onthe lines whereby to have pressure reduction before the sieves and thevaporization of a maximum quantity of the hydrocarbon phase effluents.Temperature and pressures during adsorption in the vapor phasepreferably may range from to 150 F. and the pressure from S5 to `125p.s.i.g. with lower temperatures and higher pressures favoring theadsorption of normal parains. Liquid phase adsorption may be carried outbysirnply slurrying lthe solid selective adsorbent with the lliquidhydrocarbon mixture being treated, followed by separation or decantationof the resulting treated hydrocarbon efliuent, now substantially free ofor having a substantially reduced straight chain hydrocarbon content.Liquid phase adsorption may a'lso be carried out by percolating theliquid hydrocarbon mixture tobe treated through a bed of solid adsorbentmaterial.

The molecular sieve beds may be desorbed by a number of methods whichare well known to those skilled in the art. A preferred method ofdesorbing the beds is by reducing the pressure and raising the bedtemperature in that this procedure precludes the introduction of exuse.

lt may be desirable in the practice of the invention to carry out thedesorption of n-butane from the adsorbent by employing a straight chainhydrocarbon under conditions such lthat the desorption'temperature isgreater than the critical temperature of the straight chain hydrocarbonemployed as the desorbing agent as well as the adsorbed straight chainhydrocarbon (n-butane) itself. I incorporate by reference fthedisclosure of U.S. Patent 2,818,455, issued December 31, 1957, asshowing a desorption operation carried out above the criticaltemperature of the desorbing agent.

vIn the event that the adsorptive separation operation is desired to becarried out in a-gaseous phase, that is, the hydrocarbon mixtureundergoing treatment in the vapor phase during the adsorption treatment,any suitable method for effecting' gas-solid contact may be employed,for

example, a fixed bed, -a moving bed o-r a iluidized bed or agas-entrained mass of selective adsorbent. After suiilcient time, thesolid adsorbent is separated from the resulting treated hydrocarbonVmixture, now having a reduced proportion of straight chain hydrocarbons,and the separated solid adsorbent is fthen subsequently treated todesorb the adsorbedY st-raightvchain hydrocarbons therefrom.

vDesorption of the `adsorbed hydrocarbons (straight chain) from thesolid adsorbent material may be made at any suitable temperature andpressure. The operation may be carried out at a pressure in the range ofzero to 10,000 p.s.i.g. If the desorption operation be carried out in agaseous phase, the desorbing fluid and resulting desorbed hydrocarbonsare both present in the desorption euent in the gaseous or vaporousphase. The desorption temperature and pressure in such case are adjustedto maintain fthe desorption fluid and desorbed hydrocarbonsrin ythegaseous phase. A desorption pressure in the range of to 2000 p.s.i.g.may be suitable. Pressure differences may be present between thedesorption operation and the adsorption operation. Any suitabledesorption temperature suicienitly high to effect desorption of theadsorbed straight chain hydrocarbons may be employed. Usually atemperature in the range of 400 to 1100 F. is employed during theydesorption operation. The desorption temperature should not be so highas to threaten the destruction of the adsorbent, usually limited toabout 1100 to 1300" F. Temperature alone may be suicient for desorption,but it generally is preferred to employ a hot gaseous or vaporizeddesorbing iiuid. When a straight chain hydrocarbon such as cthane,propane, butane or the like is employed to eifect desorption of theabsorbed straight chain hydrocarbon, fthe desorption operation may becarried out at a temperature above the critical temperatures of not onlythe adsorbed straight chain hydrocarbons -tobe desorbed, but also abovethe critical temperarture of the straight chain hydrocarbon employed asthe desorbing fluid or agent. Thus using propane or normal butane todesorb adsorbed n-buta-.ne from the adsorbent material, the operationmay be carried out at a temperature above Vthe critical temperature ofn-bntane, i.e. above 307 F.

Y 'From the lforegoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forthtogether with other advantages which are obvious and which Iare inherentto the process.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterhereinabove set forth or shown in the accompanying drawings is t-o beinterpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. A process of alkylating isoparainic hydrocarbons with olelinichydrocarbons inthe presence of an acid cat'- alyst comprising the stepsof contacting isoparanic hydrocarbons and oleii-nic hydrocarbons in thepresence of acid catalyst in a reaction step, withdrawing a mixture ofhydrocarbons with acid catalyst as eliluent from said reaction step,separating said eluent into an acid phase and a hydrocarbon phase in afirst separating step, separating only normal parainic hydrocarbons fromat least a portion of the hydrocarbon phase effluent in a secondseparating step while leaving isoparaflinic hydrocarbons therein,passing the normal parain separated hydrocarbon phase to -a vaporwithdrawal step, and removing both liquid and vapor phase materialseparately from said vapor withdrawal step.

2. A process as in claim l including passing liquids from 'the vaporwithdrawal step to a fractionation step for separation yof isoparaiiinichydrocarbons from said liquid.

3. A process as in claim 2 including recycling isoparafnic hydrocarbonsfrom said fractionation step yas a feed constituent -to the reactionstep.

4. A process as in claim 1 including condensing vapors from said vaporwithdrawal step and recycling them as feed to the reaction step.

5. A process as in claim 1 including passing liquid from the vaporWithdrawal step to a fractionation step Vfor .separation ofisoparaliinic hydrocarbons from said liquid and condensing vapors fromsaid vapor Withdrawal step and recycling themas Ifeed to the reactionstep.

6. A process as in claimv 1 wherein the second separating step iscarried out by passing the said portion of the hydrocarbon phaseeifluent to a molecular sieve system which separates normal parainichydrocarbons from branched chain hydrocarbons.

7. A process as in claim 1 including the step of adding lheat to saidnormal paran separated hydrocarbon phase eliluen-t before passage fromsaid vapor withdrawal step, and passing liquid from said vaporwithdrawal step to a fractionation step for separation of isoparainichydrocarbons from said liquid and condensing vapors from said vaporwithdrawal step 4and recycling them as feed to the reaction step.

8. A process of alkylating isoparainic hydrocarbons with oleiinichydrocarbons in the presence of an acid catalyst comprising the steps ofcontacting isoparafinic hydrof carbons and olelinic hydrocarbons in thepresence of acid catalyst in a reaction step, withdrawing a mixture ofhy: drocarbons 'with acid ycatalyst as eluent from said reacf tion step,separating said efiiuent into an acid phase and a hydrocarbon phase in alirst separating step, sepa-rating only normal parafiinic hydrocarbonsVfrom at least a portion of the hydrocarbon phase effluent in a secondseparating step While leaving isoparailnic hydrocarbons therein, saidreaction step and at least said rst separating step maintained undersuicient pressure to maintain the hydrocarbon phase in Iliquid form,reducing the pressure on lthe normal paraiiin eliminated hydrocarbonphase portion after one of said rst `and second separating steps,whereby to vaporize excess volatile hydrocarbons and cool saidhydrocarbon phase eiiluent, passing the pressure reduced normal paraflinseparated hydrocarbon phase portion to a vapor withdrawal step, andremoving both liquid and vapor phase material separately lfrom saidvapor withdrawal step.

9. A process las in claim 8 including passing liquids from the vaporwithdrawal system to a fractionation step for separation ofisoparaiiinic hydrocarbons from said liquid.

l0. A process as in claim 9 including recycling said isoparatiinichydrocarbons from said fractionation step to the reaction step as feed.g 11. A process as in claim 8 including condensing vapors from saidvapors withdrawal step and recycling them as feed to the reaction step.

12. A process as in claim 8 including passing liquid from the vaporwithdrawal step to a :fractionation step for separation of isoparaflinichydrocarbons Ifrom said liquid and condensing vapors from said Vaporwithdrawal 'step and recycling them as feed to the reaction step.

13. A process as in claim 8 wherein said second separating step andnormal parafnic elimination from the hydrocarbon phase effluent iscarried out in a molecular sieve arrangement operative to separatenormal parainic hydrocarbons from branched chain hydrocarbons.

14. A process as in claim `8 including adding heat to said normalparaflin eliminated hydrocarbon phase before leaving said vaporWithdrawal Istep, passing liquid from said vapor withdrawal step to afractionation step for sepf aration of isoparaliinic hydrocarbons fromsaid liquid and condensing vapors from said withdrawal step andrecycling them as yfeed to the 'reaction step.

15. A process as in claim 8 including passing the separated liquidhydrocarbons from said Vapor withdrawal step in indirect heat exchangingrelationship with the said reaction step.

16. A process as in 4claim 8 including passing all of said hydrocarbonphase effluent after said catalyst separating step to the secondsepa-rating step.

17. A process :as in claim 8 wherein all of said normal parainicseparated hydrocarbon phase eiuent is passed to said vapor withdrawalstep.

V18. A process as in claim 8 including passing all of said hydrocarbonphase eluent after catalyst separation tothe second separating step andpassing all of the normal paratiin separated hydrocarbon phase eiiuentfrom said second separating step to the said vapor withdrawal step.

19. A process of -alkylating isoparainic hydrocarbons with olefnichydrocarbons in the presence of an acid catalyst comprising the steps ofcontacting i-soparainic hydrocarbons and oleinic hydrocarbons in thepresence of acid catalyst in a reaction step, withdrawing a mixture ofhydrocarbons with acid catalyst as eifluent from said reaction step,separating said ethuent into an acid phase and a hydrocarbon phase inarst separating step, passing at least a portion `of the hydrocarbonphase eluent after catalyst separation to a second separating step andselectively removing only normal paranic hydrocarbons therefrom, whileleaving isoparafnic hydrocarbons therein, reducing the pressure on thenormal paraflinic eliminated hydrocarbon phase portion after yone ofsaid first separating step and said second sepmating step to refrigerateit and vaporize excess volatile hydrocarbons, then passing at least aportion of said :pressure reduced normal paraftinic hydrocarbon removedhydrocarbon yphase effluent in indirect heat exchanm'ng relationshipwith the reaction step, then `separating the liquid portion of thereaction step heat exchanged hydrocarbon phase from the vapor portionthereof in a vapor withdrawal step and removing vboth liquid and vaporphase material separately from said vapor withdrawal step.

20. A process as in claim 19 wherein all of the hydrocarbon phaseetliuent, after catalyst separation, is passed to the second separatingstep for normal paraffmic hydrocarbon velimination therefrom.

2l. A process as in claim 19 wherein lall of the normal paranicseparated hydrocmbon phase eiiiuent is passed in indirect heatexchanging relationship with the reaction step.

22. A process as in claim 19 wherein all of the hydrocarbon phase eluentafter catalyst separation :is passed to the second separating step fornormal paraiiinic hydrocarbon elimination and all of the normalparat-linie separated hydrocarbon phase efliuent is passed in indirectheat exchanging `relationship with the reaction step.

23. A process as in claim 19 including the additional step of recyclingliquid from the vapor withdrawal step in indirect heat exchangingrelationship with the reaction step and return to said vapor withdrawalstep.

24. A process as in claim 19 wherein said normal paranic hydrocarbonseparation in said second separating step is carried `out by a molecularsieve arrangement selectively removing normal pananic 'hydrocarbons frombranched chain hydrocarbons.

25. A lprocess as in claim 19 including passing liquid from said vaporwithdrawal step to a fractionation step for separation of isoparamnichydrocarbons yfrom said liquid.

26. A process as in claim 19 including condensing vapors `from saidvapor withdrawal step :and recycling them as efeed to the reaction step.

27. A process as in claim 19 including passing liquid from' the vaporwithdrawal step to ya third separating step for :additional vseparationof normal parainic hydrocarbons therefrom and then passing said normalparaflinic hydrocarbon separated liquid phase to la fractionation stepfor separation of isoparalhnic hydrocarbons therefrom.

28. A process as in claim including passing liquid from the vaporwithdrawal step to a third separating step and separating normalparaninic hydrocarbons from the said liquid and then passing said normalparaihnic separated liquid to a fractionation step Ifor separation ofisoparainic hydrocarbons therefrom.

29. A process of alkylating isoparainic hydrocarbons with oleiinichydrocarbons in the presence of an acid catalyst comprisingrthe steps ofcontacting isopararinic hydrocarbons and olenic hydrocarbons in thepresence of acid catalyst in a reaction step, withdrawing a mixture ofhydrocarbons with 4acid catalyst as eiuent from said reaction step,separating said eiuent into an Vacid phase and a hydrocarbon phase in afirst separating step, then separating only normal paraiinichydrocarbons from lat least a portion of the hydrocarbon phase efiuentin a 18 second separating step while leaving isopa-rathnic hydrooarbonstherein, and passing the said normal paraflinic hydrocarbon strippedhydrocarbon phase eiiluent portion to a fractionation step forseparation of isopa-rainic hydrocarbons therefrom.

30. A process as Lin claim 29 including recycling isoparainichydrocarbons from the fractionation step to the reaction step as a :feedconstituent.

31. A process as in :claim 29 wherein the second sep-arating stepemploys a molecular sieve arrangement for the segregation of normalparanic hydrocarbons yfrom branched chain hydrocarbons.

32. A process of alkylatin-g isoparaflinic hydrocarbons with olefnichydrocarbons in the presence of an acid catalyst ycomprising the stepsof cont-acting isoparaiinic hydrocarbons and olenic hydrocarbons inpresence of acid catalyst in the reaction step, withdrawing a mixture ofhydrocarbons with acid catalyst as efliuent from said 4reaction step,separating said eluent into an acid phase and a hydrocarbon phase in afirst separating step, separating only normal paranic hydrocarbons from:at least a portion of the hydrocarbon phase etiluent in a secondseparating step while leaving isoparafhnic hydrocarbons therein, saidreaction step and at least said first separating step maintained undersufficient back pressure to maintain the hydrocarbon phase in liquidform, reducing the pressure on the said normal paraihn eliminatedhydrocarbon phase after one of said iirst and second separating stepsand passing the normal paraftinic hydrocarbon stripped hydrocarbon phaseeffluent portion to a fractionation step for lseparation of isoparainichydrocarbons therefrom.

33. A process of Ialkylating isoparainic hydrocarbons with olenichydrocarbons in the presence of an acid catalyst comprising the steps ofcontacting isoparaiiinic hydrocarbons and oleiinic hydrocarbons in thepresence of acid catalyst in a reaction step, withdrawing a mixture ofhydrocarbons with acid catalyst as effluent from said react-ion step,separating Said effluent into an acid phase and a hydrocarbon phase in afirst separating step, passing at least a portion of the hydrocarbonphase to :a vapor withdrawal step, removing both liquid and vapor phasematerial separately from said vapor withdrawal step and passing at leasta portion of the vapor withdrawn Ifrom the vapor Withdrawal step to asecond separating step where normal paraiinic hydrocarbons areselectively removed from branched chain hydrocarbons.

34. A process as in claim 33 including passing said normal paranextracted hydrocarbon phase eihuent to a fractionation step forseparation ofisoparaihnic hydrocarbons from said liquid.

35. A process as in claim 33 including condensing vapors from said vaporWithdrawal step and recycling them as feed to the reaction step.

36. A process as in claim' 33 wherein said second sepa. rating stepemploys a molecular sieve arrangement to selectively extract norm-alparafinic hydrocarbons yfrom branched chain hydrocarbon-s.

37. A process as in claim 33 wherein all of said liquid phase materialfrom said vapor withdrawal step is passed to said second separatingstep.

References Cited in the file of this patent UNITED STATES PATENTSV2,412,143 Gorin et al Dec. 3,V 1946 2,429,205 .lenny et al. Oct. 21,1947 2,664,452 Putney Dec. 29, 1953 2,818,459 Gantt Dec. 31, 19572,906,796 Putney Sept. 29, 1959 OTHER narnia-:Nens

Goldsby et al.: The Oil and Gas Journal, vol. 54, No.V 20, pp. 104-107,Sept. 19, 1955.

1. A PROCESS OF ALKYLATING ISOPARAFFINIC HYDROCARBONS WITH OLEFINIVHYDROCARBONS IN THE PRESENCE OF AN ACID CATALYST COMPRISING THE STEPS OFCONTACTING ISOPARAFFINIC HYDROCARBONS AND OLEFINIC HYDROCARBONS IN THEPRESENCE OF ACID CATALYST IN A REACTION STEP, WITHDRAWING A MIXTURE OFHYDROVARBONS WITH ACID CATALYST AS EFFLUENT FROM SAID REACTION STEP,SEPARATING SAID EFFLUENT INTO AN ACID PHASE AND A HYDROCARBON PHASE IN AFIRST SEPRATING STEP, DEPARATING ONLY NORMAL PARAFFINIC HYDROCARBONSFROM AT LEAST A PORTION OF THE HYDROCARBON PHASE EFFLUENT IN A SECONDSEPARATING STEP WHILE LEAVING ISOPARAFFINIC HYDROCARBONS THEREIN,PASSING THE NORMAL PARAFFIN SEPARATED HYDROCARBON PHASE TO A VAPORWITHDRAWAL STEP, AND REMOVING BOTH